The insertion of the L1L2_Bact_P cassette created a deletion of size 891 starting at position 12769752 and ending at position 12770643 of Chromosome 7 (Genome Build GRCm39). This deletion results in the removal of functionally critical exon(s). The cassette is composed of an FRT site followed by lacZ sequence and a loxP site. This first loxP site was followed by neomycin resistance gene under the control of the human beta-actin promoter, SV40 polyA, a second FRT site and a second loxP site, and Cre-mediated excision deleted this neomycin selection cassette.